The invention relates to a rolling contact cylinder device for subjecting webs to a pressure treatment. The device has a deflection-controllable cylinder that includes a hollow cylinder rotating around its axis and forming the working cylinder circumference. It is traversed lengthwise by a non-rotatable crosshead, clearance being maintained between the crosshead around the entire inner circumference of the hollow cylinder, and having an inner support device which is mounted on the crosshead and which acts on the inner circumference of the hollow cylinder. Outer bearings are provided, which support the ends of the crosshead at outer sidewalls and which have cooperating spherical surfaces for absorbing the deflection of the crosshead, one of which is attached to the crosshead and the other to the respective sidewall. The parts of the bearing in question are combined within a ring-shaped bearing element arranged in a plane that is perpendicular to the axis of the crosshead and the bearing element being arranged in an opening in the sidewall.
A cylinder device of this kind is described in U.S. Pat. No. 4,856,154. Here, the inner support device includes a series of support plungers, having hydrostatic bearing pockets, mounted on the crosshead along the cylinder gap which act on the inner circumference of the hollow cylinder on the cylinder gap side and apply the necessary individual forces there so as to generate the line force. When subjected to the opposite forces of the support plungers, the crosshead sags within the hollow cylinder without touching its inner circumference. For this reason, separation is maintained between the crosshead and this inner circumference all around. The alignment of the hollow cylinder is not affected or is only slightly affected by the line force in the cylinder gap. The sagging crosshead, which is subject to a line load due to the line force and is supported at its ends, provides the deformation required to apply counterload to the line load along the cylinder gap.
The type of support device used is independent of the invention. In the case of the cylinder device per U.S. Pat. No. 4,856,154, the support device includes the aforementioned plungers. However, it is also possible to use a longitudinal chamber in the shape of a semicylindrical pan filled with hydraulic fluid as described in German Patent No. PS 10 26 609. Magnetic or mechanical support devices are also feasible.
In all instances, the crosshead sags as described above, and as a result the ends of the crosshead that protrude from the hollow cylinder become inclined. In the known embodiment, these ends are supported in static outer bearings which are generally arranged in the sidewalls of a cylinder housing or in calender rockers and have spherical parts to prevent jamming which allow the crosshead to sag and transfer the cylinder forces to the machine housing.
The load applied to an individual pair of spherical parts at one end of the crosshead on the order of magnitude of 100 t. As the degree of deflection of the crosshead changes, the position of the spherical parts relative to one another changes due to the substantial load and the corresponding friction, and as a result substantial tilting forces are transferred from the bearing to the machine housing. It is therefore very important that a static bearing be used in which a given bearing does not turn relative to its counterpart during operation, but rather merely shifts slightly towards its counterpart in the plane of action when a change in deflection occurs. In this case the friction problem is particularly severe, as the break-away moment must be overcome.
U.S. Pat. No. 4,856,154 also makes reference to the space limitations to which the cylinders in question are subject: The bearing at the end of the crosshead must not project beyond the diameter of the hollow cylinder, otherwise it will come into conflict with the bearing of the adjacent cylinder. Therefore any embodiment of a cylinder of this kind must be designed so that it is radially as compact as possible.
In the case of the embodiment per German Auslegeschrift No. As 22 54 392, which is in other respects similar to U.S. Pat. No. 4,856,154, the friction is limited to the spherical parts, as movement only occurs there. This embodiment has inner throw, i.e. the hollow cylinder as a whole can move in a transverse direction relative to the crosshead. Cylinder adjustment movements are carried out by the inner support device, i.e. inside the cylinder. The bearings on the ends of the crosshead only have to absorb the deflection-related changes in angle, and do not have to be shifted as a whole in the plane of action when adjustment movements are carried out.
Bearing-centered cylinders are also used, and have rotatable bearings at the ends of the hollow cylinder via which the crosshead is supported. In this case the crosshead cannot move in a transverse direction relative to the crosshead, and therefore adjustment movements cannot be made inside the cylinder itself; instead, the cylinder as a whole must be shifted, along with its crosshead. In the case of these cylinders, adjustment movements are carried out by plunger/cylinder units which act on the end of the crosshead, are arranged in the cylinder housing, and act on the ends of the crosshead. The ends of the crosshead move along guideways which are parallel to the plane of action of the cylinder or in the cylinder housing. Due to the substantial amount of friction on the spherical parts that are also present in this case, load is applied to the guideways and results in frictional forces that make it difficult to precisely control the line force in the cylinder gap. The spherical surfaces in the bearings of the crosshead are used to absorb the alignment errors of the end of the crosshead that occur when the crosshead sags. Particularly in the case of tempered cylinders, the crosshead, which may be as much as 10 meters in length, undergoes thermal-related changes in length that cause the crosshead to shift in its longitudinal direction relative to the sidewalls of the cylinder housing, which are unaffected by the thermal elongation. Particularly in the case of heated cylinders, in which the crosshead also increases in temperature in its stationary state, the ends of the cylinders can shift by a significant amount. In the case of a 10-meter-long cylinder, a temperature difference of 100 degrees [C] can result in a shift of more than one centimeter, which must be absorbed by the outer bearings, and in this respect friction also arises at full load.
There remains a need therefore, in the case of a cylinder of the type described, to eliminate the problems associated with the high level of friction on the outer bearings while preserving the desired radially compact design.
The present invention provides for a cylinder device for processing continuous material strips having a deflection-controllable cylinder that includes a hollow cylinder rotating around its axis and which forms the working cylinder circumference. It is traversed lengthwise by a non-rotatable crosshead, clearance being maintained between the crosshead around the entire inner circumference of the hollow cylinder, and has an inner support device which is mounted on the crosshead and which acts on the inner circumference of the hollow cylinder. It also has outer bearings, which support the ends of the crosshead at outer sidewalls and which have cooperating spherical surfaces for absorbing the deflection of the crosshead, one of which is attached to the crosshead and the other to the respective sidewall. The parts of the bearing in question are combined within a ring-shaped bearing element arranged in a plane that is perpendicular to the axis of the crosshead and the bearing element is arranged in an opening in the sidewall. The given end of the crosshead extends through the ring-shaped bearing element and has a shoulder in the area of the bearing element that supports the single constructional unit formed by the components of the bearing. To compensate for thermal-related changes in the length of the crosshead, an arrangement of flat slide surfaces that are hydrostatically relieved of load is provided, one of which is joined to the crosshead and the other to the sidewall. The spherical surfaces and the flat slide surfaces or faces are at least to some extent hydraulically relieved of load.
Further space-saving is achieved if the shoulder of the crosshead is provided; the shoulder creates space for the the components that transfer load.
To compensate for the thermal-related changes in length, flat slide surfaces that absorb these changes in length are provided. According to the present invention the flat slide surfaces and the spherical surfaces are at least to some extent hydraulically relieved of load.
In this case, that the outer bearings xe2x80x9care at least to some extent hydraulically freed of loadxe2x80x9d means that at least most of the load acting on the bearing surfaces is transferred through a hydraulic fluid, so that when mutual shifting of interacting surfaces occurs most of the load is carried away via the fluid, i.e. in a virtually friction-free manner, so that to this extent the friction which would otherwise be generated on the bearing surfaces and any resulting moments that would act on the guide elements are eliminated.
The bearing parts are combined to form a unit that can be arranged in an opening in the sidewall, i.e. the sidewall of the cylinder housing. As a result, one can manufacture an embodiment that saves a great deal of space, because no components such as hydraulic cylinders or the like for carrying out adjustment movements for a cylinder of this kind need be arranged outside the bearing, even if the cylinder has no inner throw. Load can be applied and adjustment movements carried out by the combined elements inside the bearing component.
Hydrostatic support for avoiding friction on the crosshead of deflection-controllable cylinders in itself related art per German Patent No. 40 11 364 C2. The aforementioned patent is based on a cylinder having inner throw, in which the crosshead has slide surfaces parallel to the plane of action along which a guide ring, which is supported by a rotatable bearing of the hollow cylinder, can be moved. Hydrostatic bearing pockets are provided to eliminate disruptive friction when the guide ring is moved along the flat slide surfaces. However, the aforementioned patent relates to straight movements within the hollow cylinder rather than to the mounting of the crosshead thereof.
In the case of a cylinder pin supported via spherical surfaces, hydraulically relieving load thereof is generally known from U.S. Pat. No. 5,382,096, including in the case of a combination of spherical surfaces and flat surfaces. However, this patent involves a rotatable bearing for a cylinder pin rather than the static bearing described in the present invention.
The present invention can be implemented in two ways, which differ from one another in terms of design.
In a first of embodiment a plunger/cylinder unit having an axis that applies the support load is provided. A first component of the plunger/cylinder unit is non-movably attached to a given sidewall and the other component of the plunger/cylinder unit moves linearly relative to the first component and can incline relative to the crosshead in its plane of deflection. The two components of the plunger/cylinder unit move linearly relative to one another but cannot be inclined relative to one another. Here, the flexibility relating to the inclination that occurs when the crosshead sags is achieved because the first component of the plunger/cylinder unit rests on the crosshead.
In a second embodiment, one component of the plunger/cylinder unit is rigidly attached to the sidewall, while the other component is rigidly attached to the crosshead and can incline relative to the first component in the plane of deflection. Here the flexibility is achieved within the plunger/cylinder unit, the components of which can be inclined relative to one another thanks to the clearance between them and thanks to seals designed to bridge this clearance.
To avoid tilting moments, the spherical surfaces and the flat slide surfaces should be ring-shaped and should be coaxial with the plunger/cylinder unit.
In the embodiment having spherical surfaces, the plunger/cylinder unit acts on disc-shaped component on whose underside a flat slide surface is formed, and the other flat slide surface is provided on the upper side of disc-shaped cap component, which has a convex spherical surface on its underside. The other concave spherical surface is provided on a disc-shaped bowl component arranged in the bottom-most position.
The present invention teaches a design for the plunger/cylinder unit in which the component having a flat slide surface is the base of cup-shaped cylinder of plunger/cylinder unit. The plunger of plunger/cylinder unit has two separate casings and encloses the wall of the cylinder between its walls, and the pressure chamber inside the wall and above the upper side of the base can be filled with pressure (hydraulic) fluid via a port.
The base of the plunger/cylinder unit and the base of the bowl component form the boundaries of the pressure relief chamber in the axial direction, and the annular seals form its boundaries in the radial direction. The cap component is subject to the pressure of the hydraulic fluid on both sides, and, as the action surfaces match one another, is hydraulically freed of load, i.e. it is load-free. The pressure of the hydraulic fluid tends to raise the base of the plunger/cylinder unit off the bowl component. If no pressure is present in the pressure relief chamber, the components rest on one another via the flat slide surfaces that are provided radially outside the chamber and via the spherical surfaces. If pressure is present in the pressure relief chamber, both pairs of surfaces are hydraulically freed of load, i.e. the load of the plunger/cylinder unit is carried away via the hydraulic fluid.
If the annular seals have roughly the same diameter, the cap component also cannot be kept essentially completely load-free.
It is useful to provide, outside the annular seals, overflow oil collection pockets which collect the overflow oil that leaks radially outwards from the pressure relief chamber at the annular seals. Specifically, these can be arranged so that the overflow collection pocket of the side surfaces is arranged on the component and the overflow collection pocket of the spherical surfaces is arranged on the bowl component.
According to one useful design, the annular seals of the pressure relief chamber form one boundary of the overflow oil collection pockets, and additional annular seals concentric with the aforementioned annular seals form the other boundary.
According to another aspect of the invention, the fluid may be drained off from the overflow collection pockets via holes which lead to an overflow collection chamber connected to an extraction device. This arrangement has the additional advantage that the overflow oil of the plunger/cylinder unit, which is also subject to considerable pressure, can also collect in the overflow oil collection chamber and can be drained off along with the other overflow oil.
It is useful to press the components of the pressure relief chamber together via spring pressure, so as to ensure an initial seal.
In the case of the embodiment in which, when the crosshead sags, flexibility is provided in the plunger/cylinder unit itself, the plunger/cylinder unit can be designed such that the components of the plunger/cylinder unit can be inclined relative to one another by a small angle that correspond to the inclination of the ends of the crosshead when deflected. This serves to maintain the seal of the pressure chamber of the plunger/cylinder unit. With regard to the pressure relief chamber, the outer radial boundary is formed by an annular seal. The pressure relief chamber is formed beneath the base of the first component of the plunger/cylinder unit.
In the case of both embodiments, it is useful if the pressure in the pressure relief chamber is removed via the pressure in the pressure compartment via a fluid connection created via a throttle bore. This has the additional advantage that the release pressure automatically matches the load pressure.